Julian Castro is using the sudden national spotlight on Texas to carve out a role as a fierce White House critic and a leading voice on Hispanic issues as he builds a case for a potential 2020 president run.

The former Obama administration Cabinet secretary has been publicly blasting President Donald Trump on a host of issues related to Texas. Notably, Castro bucked his party’s politically-neutral approach to Hurricane Harvey recovery – and went on national television to slam Trump’s visit to Texas to comfort storm victims.

He’s also using his perch as a Latino leader in the state with the second largest Hispanic population to condemn the White House’s plan to end protections for children who were brought to the country illegally.

Castro’s moves are a preview of his potential pitch in what could be a crowded 2020 Democratic field. A month ago, he launched a political action committee, cited by political watchers as the first step toward a potential presidential bid.

He also accepted a teaching job at the University of Texas’s LBJ School of Public Affairs, a low-profile gig that could leave him time to travel to swing states such as North Carolina, where he’ll headline a dinner with the Guilford County Democratic Party later this month.

“I count myself as one of those folks who will do what I can to push back on the terrible agenda of this president,” Castro said in an interview with the Star-Telegram last week.

“For Democrats, the future is the line between Arizona, Texas and Florida, and those 78 electoral votes are not as far off as people think,” said Castro. “The real movement that we stand to see in the coming years are those 78 electoral votes going Democratic… and I believe that Donald Trump is accelerating that.”

The former San Antonio mayor believes the party’s future runs through states with rapidly changing demographics that will boost the Latino vote.

“Florida is already winnable. Texas is getting closer because of Trump… The combination of the growing resentment among Hispanic and other voters in all of those states… could grow that,” he added.

Castro and his identical twin brother, long viewed as a political team, are among the Democratic Latino leaders of the future. Joaquin Castro represents a Latino-heavy congressional district that includes parts of San Antonio.

Julian Castro was among Democrats’ potential vice presidential picks in 2016, billed as having the potential to excite Hispanic voters for Clinton.

One drawback: His inability to fluently speak Spanish. Castro pushed back against reports that he was taking classes to learn Spanish for that role, saying he’s “always spoken some Spanish, and understands Spanish,” though is not currently fluent.

Clinton instead chose Virginia Sen. Tim Kaine, who does speak Spanish, and went on to perform worse among Latinos than President Barack Obama in 2012. A Pew Research Center survey before the election suggested much of that gap came from Hispanic millennials, who made up nearly half of the Latino voters.

Some Democrats are eager for the young, telegenic Castro brothers to lead the party’s message against Trump,particularly on issues related to Hispanic voters.

“To have a strong and articulate voice like Julian Castro talking about those issues is very helpful, not just in Texas, but across the entire country,” said Texas Democratic strategist Matt Angle, who ran the Democratic Congressional Campaign Committee in 1996 and 1998.

But Castro’s abilities as a national candidate haven’t been tested.

“[Julian] Castro just isn’t real to me yet,” said one national Democratic strategist. “Maybe he has the political timber… but right now he’s just one of 20.”

Castro’s proposed electoral route could prove to be a bumpy path. Though strong Latino turnout can be helpful in a number of important states, strategists cautioned Texas remains a huge challenge.

“Certainly the [electoral vote] math works,” said Angle. “I’m also realistic enough to know that there are other ways to make that math work to get to 270 electoral votes, and that it costs a lot of money to flip a state like Texas.”

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Castro was optimistic that Trump’s presidency will help give Texas Democrats the push they need.

“There’s an unprecedented level of disrespect that Trump has shown to the Hispanic community that I believe is not falling on deaf ears,” said Castro, who pointed to Trump’s plans to end a program to protect young undocumented immigrants as one example.

Texas has the second largest population of so-called Dreamers, who were brought to the country by parents at a young age.

“Undoubtedly it accelerates the shift from a Republican state to a competitive, and then Democratic state,” he said.

So far that shift has been happening more slowly in Texas than Democrats once expected. Census data showed only a modest increase in Hispanic turnout in Texas in 2016, not the large increase strategists predicted in response to Trump.

Castro is working to keep the heat on Trump in his home state. In the wake of a devastating hurricane that drew national attention to Texas, he went on national TV attacking Trump’s response.

“We’ve seen now, on several occasions, whether it’s this or Charlottesville, President Trump just cannot find it within himself to be centered around others, to be a true public servant. It’s always about him,” Castro said on CNN after Trump’s visit.

Those comments put Castro at odds with some Texans from his own party. Texas’s Democratic congressional delegation, including Joaquin Castro, struck a much more conciliatory tone after the hurricane, joining with their GOP colleagues for a press conference on Capitol Hill to show political unity on the issue.

Some also joined Vice President Mike Pence at his residence later that night to discuss recovery plans, which included nearly $16 billion emergency funding. That deal was achieved through negotiations between Trump and Senate Democrats – who praised the president’s willingness to work with them.